Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$140.54	3.632%	$145.6444	$145.64	$145.65	$145.60
Purchase #2	$89.71	9.281%	$98.036	$98.04	$98.05	$98.00
Purchase #3	$205.78	6.592%	$219.345	$219.35	$219.35	$219.30
Purchase #4	$176.52	9.667%	$193.5842	$193.58	$193.60	$193.60
Purchase #5	$11.98	6.291%	$12.7337	$12.73	$12.75	$12.70
Purchase #6	$199.50	7.564%	$214.5902	$214.59	$214.60	$214.60
Purchase #7	$216.40	12.689%	$243.859	$243.86	$243.85	$243.90
7 purchase totals =	$1,040.43		$1,127.7925	$1,127.79	$1,127.85	$1,127.70